docs: def external(name, value, dtype=tf.sg_floatx, summary=True, regularizer=None, trainable=True):
      r"""Creates a tensor variable of which initial values are `value`.
      
      For example,
      
      ```
      external("external", [3,3,1,2])
      => [3. 3. 1. 2.]
      ```
      
      Args:
        name: The name of new variable.
        value: A constant value (or list) of output type `dtype`.
        dtype: The type of the elements of the resulting tensor.
        summary: If True, add this constant to tensor board summary.
        regularizer:  A (Tensor -> Tensor or None) function; the result of applying it on a newly created variable
          will be added to the collection tf.GraphKeys.REGULARIZATION_LOSSES and can be used for regularization
        trainable: If True, add this constant to trainable collection. Default is True.
  
      Returns:
        A `Variable`. Has the same contents as `value` of `dtype`. 
      """
      # create variable
      x = tf.get_variable(name,
                          initializer=tf.constant(value, dtype=dtype),
                          regularizer=regularizer, trainable=trainable)
      # add summary
      if summary:
          tf.sg_summary_param(x)
      return x